Shellfish or Iodine Allergy

Let your doctor, nurse, and X-ray technician know if you have an allergy to shellfish or iodine before you have an X-ray procedure that requires an injection of dye (contrast solution). This dye is sometimes used to make things more visible during procedures like a cardiac catheterization, a computed tomography (CT) scan, or a magnetic resonance imaging (MRI) scan.

If you are allergic to shellfish or iodine, your doctor may decide not to use the dye for the procedure. If dye is needed to make the procedure effective, a special type of dye may be used. You may also be given medicine that will reduce your chance of an allergic reaction to the dye.